Newly prepared single crystals of [Co(ii)(dabco)(NCS)2(MeOH)2]·dabco (1-pink; dabco: 1,4-diazabicyclo[2.2.2]octane) showed chromotropic behaviour in the solid state, changing from pink to blue upon heating or grinding. The complex 1-pink exhibited a two-dimensional orthogonal network structure with the coordination chain of -dabco-Co- bridged by hydrogen bonds between coordinative methanol and a second dabco molecule, where the methanol molecule was trapped by coordinative and hydrogen bonds. Chromism was demonstrated to stem from the quantitative desorption of methanol from 1-pink to produce [Co(ii)(dabco)(NCS)2]·dabco (1-blue(c)) by thermogravimetric (TG) and temperature controlled gas chromatography-mass spectrometry (GC-MS) analyses, and powder X-ray diffraction (XRD) analysis suggests that the transformation between the crystalline phases of 1-pink and 1-blue(c) occurred with similar lattice parameters. Furthermore, the desolvated species showed chemo-chromic behaviour due to the selective size- and polarity-dependent adsorption of solvent molecules.

Ionic single crystals of the polyoxometalate [Mo V 2 Mo VI 16 O 54 (SO 3 ) 2 ] 6salted with tetrabutylammonium were found to exhibit dielectric anomalies at 235 and 302 K. The clear DSC peak at 235 K indicates the first-order nature of transition. The next transition at 302 K was concluded to be secondorder in nature, demonstrating the existence of three different phases (α, , and γ). Temperature-dependent single-crystal X- [a]

New mixed-valence polyoxometalate (POM)-organic hybrids, i.e., [Na(SO3)2(PrPO3)4MoV4MoVI14O49]5− and [Na(SO3)2(t-BuPO3)4MoV4MoVI14O49]5−, were synthesised and studied using crystallography, solution-phase 31P NMR, and electrochemistry. These species comprise four organic phosphonates bonded to a metal oxide cage. Derivatization was achieved by considering the pKa of the organic phosphonates and sulfite anions that acted as templates for the self-assembly of molybdate with POM. All the clusters were prepared in a water-acetonitrile mixed solvent system by a one-pot procedure and showed multi-step redox cycles, revealing that [Na(SO3)2(RPO3)4MoV4MoVI14O49]5− comprised a unique set of covalently grafted POM-organic hybrids with high redox activity.

We report reversible structural transformation that occurs in two ladder compounds: Cu2CO3(ClO4)2(NH3)6 (1) and Cu2CO3(ClO4)2(NH3)5(H2O) (2), when they are exposed to gaseous vapors. The ladder structures of both 1 and 2 consist of two Cu2+ ions and one CO32− ion. In 1, the Cu2+ ions are coordinated by three NH3 molecules on each side, while those in 2 are coordinated by three NH3 molecules on one side, and two NH3 molecules and one H2O molecule on the other side. We demonstrated reversible transformation of 1 and 2 via the exposure of 1 to H2O vapor and the exposure of 2 to NH3 vapor using a simple bench-scale method. The minor structural change observed led to a significant difference in physical properties, which we observed using several methods.

Thermally induced circular rotation of anionic [Co(OCN)3(dabco)]∞ chains was observed in the quaternary molecular crystal of Co(dabco)K(OCN)3. The orientational angle of the ligand molecules was a function of temperature. This...